The Federal Reserve's efforts to cut back sharply on the amount of credit available in the banking system for the last month are beginning to bite.

The Fed, architect of the nation's monetary policy, is taking the steps in order to hold down the rate of inflation. Sharp increases in the money supply and plentiful credit are though by most economists to stimulate inflation.

The Fed's vigilance in the last month has pushed interest rates to record levels. The prime rate has hit the 20 percent peak of last spring, and rates in the open market -- where banks and many companies raise funds -- are higher than last spring.

Now there is some evidence that funds are more than just expensive. Some analysts say money is drying up in the short-term credit markets in much the same way it already evaporated in the long-term bond and mortgage markets where for several months investors have been unwilling to commit funds because of uncertainty about inflation and rising interest rates.

"The Fed has really put the squeeze on," said Patrick Savin, chief money analyst for the big brokerage firm Drexel Burnham Lambert Inc.

"Some banks -- not this one -- have been having a problem this week," according to George Baker, senior executive vice president of Chicago's Continental Illinois National Bank, one of the nations's biggest and most respected financial institutions.

Other bankers say that the problem is not one of unavailability of credit, but a reluctance on the part of banks to pay the high rates to obtain funds and borrow money for any but the shortest period of time, hoping that rates will go down.

As a result, on Thursday the interest rate on one-month certificates of deposit climbed to 21 3/8 percent, according to William Sullivan of the Bank of New York. Today banks paid 21 percent to borrow for one month. Banks normally try to borrow for three months. The three-month rate was 21 1/4 percent Thursday, but it fell to 20.65 percent today, Sullivan said.

Banks are finding it increasing expensive and at times difficult to raise the funds they need to supply their borrowers. Prices of stocks have fallen sharply in the last few weeks, in large part because of the interest-rate burden.

Commodities futures prices have tumbled dramatically as speculators became convinced that the Federal Reserve was not going to relax tis policies. There was near-panic trading on Thursday as most commodities prices fell the maximum amount permitted under trading rules adopted by the various exchanges in New York, Chicago and elsewhere.

By today, conditions in almost all the markets had calmed considerably.

Thursday, as commodities prices fell precipitously for the ninth day in a row, there were rumors that some brokerage firms were in the same kinds of financial difficulties that they were in last spring, when the collapse of the silver market nearly put several out of business.

But a spokesman for the New York Stock Exchange said its top surveillance officials conducted a special audit of its member firms and found that none were having difficulties. "There were big margin calls, but everyone was meeting them with no problems," a Wall Street official said.

The Commodity Exchange of New York announced today that because of the speculative fever on the exchange's silver market, investors will have to put up more cash to buy silver contracts, beginning next Monday.

In commodities trading, investors put up a small cash outlay -- called a margin -- to control a contract often worth many times more than the value of the margin. When they buy a contract -- it specifies the purchaser either must buy or sell a commodity at a certain price and date in the future -- investors are betting that the price of the commodity will move in a certain direction. If they are wrong, they must make up their losses each day by adding to their margin.

When a broker demands more money from a customer or when the futures exchange demands more money from a broker to cover its accounts, industry officials term the demand a margin call. When the Hunt brothers of Texas and other big investors who bet silver prices would rise could not cover their margin calls during the collapse of silver prices, the brokers had to cover the margin calls themselves, pushing many to the brink of collapse.